Low nitrogen optimization design and numerical simulation of burner for direct thermal desorption of contaminated soil
SHEN Yuandong1,, ZHAN Mingxiu1, LI Shaohua2, YUE Yong2, XU You3, QIAN Peihao4, GU Hailin1, JI Longjie5, JIAO Wentao5,,, CHI Zuohe1 1.School of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, China 2.Sinochem Environment Holdings Co., Ltd, Beijing 100045, China 3.Zhejiang XiZi United Engineering Co., Ltd., Hangzhou 310021, China 4.Hangzhou HongHe Energy and Environment Technology Co., Ltd, Hangzhou 310018, China 5.State Key Laboratory of Urban and Regional Research, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
Abstract:In order to solve the problem of high NOx emission from the burner of the second combustion chamber of the direct thermal desorption equipment. The input and output energy balance equations were established by using the heat balance calculation method, and the required fuel and combustion supporting air volume when the temperature of the secondary combustion chamber was maintained at 1 100 ℃ were obtained. Combined with air classification technology, fuel classification technology and partial premixed combustion technology, the burner was optimized, and its combustion was numerically simulated. The heat balance calculation results showed that the fuel gas and combustion supporting air volume required to maintain the combustion temperature of the second combustion chamber at 1 100 ℃ were 1 003 and 22 066 m3·h?1, respectively. The results showed that increasing the gas premixing nozzle can significantly strengthen the gas/air mixing, make the combustion more rapid, prevented the lagging flame from scouring the wall, dispersed the flame and avoided local high temperature. The addition of secondary air channel can reduce the outlet flow rate of air, prevent misfire, facilitate the radial diffusion of gas and avoid flame concentration. The above two methods can effectively reduce NOx emissions, and partial premixing of gas can also effectively reduce the concentration of carbon monoxide at the outlet. After the gas premixing nozzle and secondary air channel were adopted at the same time, the NOx concentration was stable at about 45 mg·m?3, and the NOx emission was reduced by 85% compared with the existing burner. The research results can provide a reference for the low nitrogen design of the secondary combustion chamber burner of the direct thermal desorption equipment. Key words:soil remediation/ thermal desorption technique/ heat balance calculation/ low nitrogen combustion.
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1.School of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, China 2.Sinochem Environment Holdings Co., Ltd, Beijing 100045, China 3.Zhejiang XiZi United Engineering Co., Ltd., Hangzhou 310021, China 4.Hangzhou HongHe Energy and Environment Technology Co., Ltd, Hangzhou 310018, China 5.State Key Laboratory of Urban and Regional Research, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China Received Date: 2020-10-19 Accepted Date: 2021-10-05 Available Online: 2021-11-18 Keywords:soil remediation/ thermal desorption technique/ heat balance calculation/ low nitrogen combustion Abstract:In order to solve the problem of high NOx emission from the burner of the second combustion chamber of the direct thermal desorption equipment. The input and output energy balance equations were established by using the heat balance calculation method, and the required fuel and combustion supporting air volume when the temperature of the secondary combustion chamber was maintained at 1 100 ℃ were obtained. Combined with air classification technology, fuel classification technology and partial premixed combustion technology, the burner was optimized, and its combustion was numerically simulated. The heat balance calculation results showed that the fuel gas and combustion supporting air volume required to maintain the combustion temperature of the second combustion chamber at 1 100 ℃ were 1 003 and 22 066 m3·h?1, respectively. The results showed that increasing the gas premixing nozzle can significantly strengthen the gas/air mixing, make the combustion more rapid, prevented the lagging flame from scouring the wall, dispersed the flame and avoided local high temperature. The addition of secondary air channel can reduce the outlet flow rate of air, prevent misfire, facilitate the radial diffusion of gas and avoid flame concentration. The above two methods can effectively reduce NOx emissions, and partial premixing of gas can also effectively reduce the concentration of carbon monoxide at the outlet. After the gas premixing nozzle and secondary air channel were adopted at the same time, the NOx concentration was stable at about 45 mg·m?3, and the NOx emission was reduced by 85% compared with the existing burner. The research results can provide a reference for the low nitrogen design of the secondary combustion chamber burner of the direct thermal desorption equipment.
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